Ball joints and other types of pivot joints are commonly provided with boot seals to prevent entry of dirt and other foreign materials into housing openings and to hold excess lubricant. The boot seal should be constructed in such a manner as to allow a small portion of the lubricant to escape without dislodging the seal. Several known boot seals which have been more or less satisfactory in their mode of operation are disclosed in U.S. Pat. Nos. 3,021,157; 3,262,706; 3,322,445; 3,403,932; 3,441,298; and 3,476,417.
In the past, difficulties have been encountered in using boot seals due to variations in the diameter of the housing with which the boot seal is associated. Unless the diameter of the outer side surface of the housing is held within a relatively small tolerance range, e.g., plus or minus 0.005 inches, the desired sealing relationship will not be obtained between the outer side surface and a boot seal. At the same time, cost considerations dictate that housings be forged or otherwise formed such that their outside surfaces have any diameter within a relatively wide tolerance range. The diameter of an asforged housing surface may vary from a nominal diameter by as much as plus or minus 0.010 inches. Expensive machining of the outer side surface of the housing is thus required to achieve the relatively small tolerance range that insures the desired sealing relationship between the housing and a boot seal. The machining reduces the cost savings offered by forging the housings.
In an effort to position a boot seal automatically relative to an as-forged surface of a joint housing, it has been suggested that the seal could be provided with relatively short positioning fingers and relatively long retaining fingers. The relatively short positioning fingers engage the outer side surface of the housing to compensate for irregularities in the as-forged surface. The relatively long retaining fingers grip the side surface of the housing to hold the seal in place. The manner in which such a boot seal would cooperate with a joint housing is disclosed in U.S. Pat. No. 3,310,326.